In general, a hybrid vehicle in a broad sense means a vehicle driven by efficiently combining two or more different kinds of power sources, but in most cases, means a vehicle obtaining driving force from an engine, which is driven by fuel, and an electric motor, which is driven by power of a battery, and is called a hybrid electric vehicle (HEV).
A high voltage battery for providing driving force of the electric motor is essentially mounted in the hybrid electric vehicle and the like, and the high voltage battery supplies necessary power while repeating charging/discharging during travelling of the vehicle.
A high-output lithium ion (polymer) battery (LiPB) is widely used as the high-voltage battery in the hybrid electric vehicle, and the lithium ion battery has a problem below.
Particularly, when the lithium ion battery is overcharged, flammable gas is generated by decomposition of an electrolyte which is an exothermic reaction, and thus an interval pressure of the battery is increased to accompany an increase in a thickness of the battery. Thus, a temperature is increased and a short of circuit is incurred, and flammable gas is ignited and causes a fire, thereby causing a fatal result to safety of a driver and a vehicle.
Particularly, in a battery of a hybrid vehicle or a fuel cell vehicle, a plurality of batteries is modulated and mounted for a high voltage, so that there is a high possibility that a problem is incurred in safety when overcharge and ignition are incurred.
In order to prevent the battery from being overcharged, a stable and preventing device having various structures has been developed.
However, in the battery overcharge preventing device in the related art, a battery cell is damaged when the battery cell configuring a battery module is expanded, so that there is a problem in that poisonous gas is discharged to the outside to cause environmental pollution.
The battery overcharge preventing device in the related art has a complex structure for being mounted in the battery module, and is difficult to be replaced.